Having contacts in the People page is important because it's where we pull from to auto-fill personalized information in the dynamic fields in your templates. Make sure you have at least a name and an email address for each contact in your CSV and that you map to those fields.
Select your group (or create a new one) in the People tab.
Click Group Actions and select Import CSV.
Locate the file on your computer and select it.
Map the columns in your CSV to their respective fields in Sales Connect. Click Next when done.